Hard as nails

How many boxers have retired undefeated (and never come back!)?asked Jerry Carter

I suspect you mean world champions, as there are obviously quite a few boxers who have stopped after a fight or two (the former England cricket captain Andrew Flintoff, for example).

The answer is that only ten men have won one of the four major world championship belts (WBA, WBC, IBF or WBO), retired undefeated and resisted the temptation to make a comeback.

The only heavyweight among them is Rocky Marciano, who won all 49 of his fights. Arguably the most famous of the others is Britain's Joe Calzaghe, who won all 46 of his fights, including 21 world super-middleweight title defences.